Hepatitis B Surface Antigen (HBsAg) positive donors identified from 1970 to the present will be enrolled to determine the long-term consequences of Hepatitis B Virus (HBV) infection in asymptomatic blood donors. Donors will be identified by the Washington Red Cross and the Department of Transfusion Medicine, NIH. Emphasis will be placed on those donors found HBsAg positive 5 or more years ago. The primary study goals will be to determine what proportion of asymptomatic HBsAg positive donors have developed evidence of chronic hepatitis and what proportion may have evolved into hepatocellular carcinoma (HCC). A major thrust of the study will be the early detection of HCC by measurement of alpha-fetoprotein. Early HCC appears amenable to surgical intervention. Donors found to have HCC will be referred to the NIH Surgical Service under a separate protocol. Once enrolled, donors will be followed for at lease 5 years.